Ultrafast Two-Color X-Ray Emission Spectroscopy Reveals Excited State Landscape in a Base Metal Dyad.

Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light-induced proton reduction systems. Developing competitive base metal dyads is mandatory for a more sustainable future. However, the electron transfer mechanisms from the photosensitizer to the proton reduction catalyst in base metal dyads remain so far unexplored. A Fe─Co dyad that exhibits photocatalytic H2 production activity is studied using femtosecond X-ray emission spectroscopy, complemented by ultrafast optical spectroscopy and theoretical time-dependent DFT calculations, to understand the electronic and structural dynamics after photoexcitation and during the subsequent charge transfer process from the FeII photosensitizer to the cobaloxime catalyst. This novel approach enables the simultaneous measurement of the transient X-ray emission at the iron and cobalt K-edges in a two-color experiment. With this methodology, the excited state dynamics are correlated to the electron transfer processes, and evidence of the Fe→Co electron transfer as an initial step of proton reduction activity is unraveled.

Metabolomic profiling and biological investigation of Tabebuia Aurea (Silva Manso) leaves, family Bignoniaceae.

Both ethyl acetate and aqueous fractions of Tabebuia aurea leaves exhibited noteworthy antioxidant and nephroprotective activities against carbon tetrachloride (CCl4)-induced nephrotoxicity in rats, as evidenced by the remarkable improvements of renal serum biomarkers and histopathological features. Additionally, the ethyl acetate fraction displayed a prominent in vitro antitrypanosomal activity against Trypanosoma brucei; consequently, the leaves were subjected to LC-HR-ESI-MS metabolomic profiling to discover the constituents that possibly underlie their bioactivities. Therefore, ten metabolites were characterized, mostly dominated by flavonoids. Interestingly, two identified constituents viz., 3,9,12,15-octadecatetraenoic acid (9) and 9,11,13-octadecatrienoic acid (10) are reported firstly herein from the genus Tabebuia. Furthermore, among the dereplicated constituents, rutin (5) and kaempferol 3-O-rutinoside (6) exhibited the highest docking scores as effective antitrypanosomal compounds.

Increment of Lysosomal Biogenesis by Combined Extracts of Gum Arabic, Parsley, and Corn Silk: A Reparative Mechanism in Mice Renal Cells.

Gum Arabic (GA), parsley, and corn silk have been traditionally used for renal failure patients worldwide. This study aimed at probing the mechanism of the combined extracts, namely, GA (3 g/kg/day), parsley (1 g/kg/day), and corn silk (200 mg/kg/day), as nephroprotective agents in mice after amikacin (1.2 g/kg) single dose through exploration of their action on G-protein coupled receptors (GPR) 41 and 43 and the ensuing lysosomal biogenesis. Western blotting was employed for renal levels of bcl-2-associated X protein (BAX) and cytosolic cathepsin D; cell death markers, nuclear transcription factor EB (TFEB), and lysosomal associated membrane protein-1 (LAMP-1); and lysosomal biogenesis indicators. Liquid chromatography-mass spectrometry (LC-MS) and docking were also employed. After amikacin treatment, BAX and cathepsin D levels were upregulated while LAMP-1 and nuclear TFEB levels were inhibited. The combined extracts inhibited BAX and cytosolic cathepsin D but upregulated LAMP-1 and nuclear TFEB levels. Docking confirmed GPR modulatory signaling. The combined extracts showed GPR signal modulatory properties that triggered lysosome synthesis and contributed to reversing the adverse effects of amikacin on renal tissues.

Tecoma stans: Alkaloid Profile and Antimicrobial Activity.

AIM: Tecoma stans (L.) Kunth is a promising species in the trumpet creeper family Bignoniaceae. This study aimed at showing the antibacterial and antifungal potentials of T. stans methanolic leaf extract (TSME) correlated to its phytoconstituents. MATERIALS AND METHODS: The antimicrobial potential of TSME was evaluated using agar diffusion method. The main alkaloids were separated on silica gel column and identified using nuclear magnetic resonance spectral analysis. Molecular docking was performed for the isolated compounds against MurD ligase, penicillin-binding protein, and dihydropteroate synthase enzyme to rationalize the observed antibacterial effect. RESULTS AND DISCUSSION: TSME showed significant antibacterial effect against all tested microorganisms with comparable minimum inhibitory concentration (MIC) to the ampicillin and gentamicin with MIC values ranging between 0.98 and 1.95 µg/mL, in addition to a promising antifungal effect when compared to amphotericin with MIC values 3.9 and 15.63 µg/mL for Aspergillus flavus and Candida albicans, respectively. Several alkaloids were separated, purified, and identified as tecostanine, 4-OH tecomanine, 5-hydroxyskytanthine, and tecomanine, which were previously isolated from T. stans. The docking study showed that the alkaloids bind in a similar fashion to the co-crystallized ligands of the crystal structures of MurD ligase. The binding poses and scores in the case of penicillin-binding protein and dihydropteroate synthase did not match the co-crystallized ligands in their crystal structures. The in silico results suggest an antibacterial mechanism that involves the inhibition of MurD ligase. CONCLUSION: T. stans alkaloids could represent the basic skeleton for a powerful antimicrobial agent.